In contemporary aircraft construction, components such as wings, engine nacelles, and empennages, or tail units, are used which are enveloped by a flow of surrounding air in flight operation. In principle, two different flow conditions manifest in the air flow enveloping the aircraft components. In the layers of flow further removed from the aircraft component there exists a frictionless outer flow, and in flow layers of the air flowing directly past the aircraft component there exists a boundary layer flow having a laminar and/or turbulent flow. Such boundary layer flows are mostly not turbulent over the entire length of the flow body or of the aircraft component but, when viewed in the direction of flow, initially generally present an area of laminar flow and then an area of turbulent flow, with the laminar area of flow being substantially smaller than the manifesting area of turbulent flow. In the case of commercial aircraft used in middle-range operation this distribution results in a frictional contribution of approx. 50% to the overall resistance of the aircraft. In order to reduce the air resistance, transition controls were proposed in the prior art whereby a component-specific preservation of the laminar boundary layer flow may be achieved with the aid of boundary layer suction.
Previous boundary layer suction systems make use of pump/compressor units for extraction of the boundary layer flowing around the flow body. Extraction is effected locally at components such as wing, engine nacelle, or vertical tail, wherein the electric energy to be expended for the operation of the pump/compressor units is furnished, e.g., via hydraulic systems while for example making use of driving fluid from the air-conditioning system of the aircraft for operating the pump. The pumps are connected via conduit systems to openings at the surface, for instance of a wing, in order to be able to extract the air mass flow.
The pump/compressor unit of the known suction systems must, however, be taken into account in the energy balance and also in the weight analysis of the aircraft and must inevitably be considered to be added expenditure. The additional weight introduced on board an aircraft by these systems and the added energy consumption result in a deteriorated efficiency of the aircraft.